Controllable Preparation Of Molybdenum Telluride And Performance Study Of Photodetectors Based On Vertical Heterostructure

In recent years,transition metal chalcogenides(TMDs)have become more and more interesting due to their excellent physical properties such as mechanical,electrical,optical and thermal properties.MoTe2 is a kind of TMDs material with an anisotropic crystal structure,high carrier mobility,and absorption spectrum covering the visible to near-infrared range.Therefore,it has great potential in electronics and optoelectronics.So far,the technology for synthesizing large area and high-quality MoTe2 crystals has not yet matured,making it difficult to apply MoTe2 to the practical application.In response to these problems,this paper first studied the technology of CVD growth of MoTe2 two-dimensional atomic crystals,and explored the growth conditions and growth mechanism.Then,an infrared photodetector based on graphene/MoTe2/graphene vertical heterostructure was prepared and its photodetection performance in the near-infrared region was studied.The main research results are as follows:1.The growth conditions of MoTe2 two-dimensional atomic crystals by salt-assisted CVD on SiO2/Si substrate were investigated.The effects of growth temperature and growth time on growth results were systematically studied.After a series of comparative experiments,we think the optimal growth temperature and time were 750 C and 5 min,respectively.After optimizing the growth conditions,a large area of 1T' MoTe2(size greater than 100 ?m)was obtained.2.A 1T' phase MoTe2 single crystal was grown on a sapphire substrate,and the effect of the substrate on the growth results was analyzed.3.The mechanism of CVD growth of MoTe2 was discussed.The necessity of salt-assisted synthesis of MoTe2 was expounded,and the reason why the structure of MoTe2 was 1T' phase was explained.4.The graphene/MoTe2/graphene vertical van der Waals heterostructure was prepared by mechanical exfoliation method and mechanical transfer technique,and its continuous spectral response in the near infrared(800-1800 nm)was tested.The detector exhibits excellent performance.Under laser irradiation of ?=1600 nm and P=4 mW,the responsivity is R=217 mA/W,and the detectivity is D*=4×109 Johns,and the response time is 47 ?s.